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Question: 20130021 Status

Source 1:   Heme & Lymph Neo Manual & DB
Source 2:  

Histology/Grade--Heme & Lymphoid Neoplasms: Why is the classification change not explained in the hematopoietic database abstractor notes for follicular lymphoma (FL) (grade 1, 2, or 3)? If grade 1 is not being seperated from grade 2 and any FL with even a few centroblasts is being labelled as such, when will grade 1 be used on it's own? See discussion.

I am seeing frequent use of "low grade" and "grade 1-2" in the pathology diagnosis for histological classification for grade 1 and grade 2 FL. I understand the correct code for these cases is 9691/3 Grade 2. Apparently WHO 2008 is grouping grade 1 (9695/3) as grade 1-2 due to minimal difference in patient outcome compared to grade 2.

When the latest WHO classification for heme neoplasms was written in 2008, there was a lot of controversy about whether or not the FL grading system was useful or not. A number of papers have been written saying grades 1 and 2 do not have a statistically different survival or transformation rate. Since the controversy had not been settled by the clinical world, WHO recommended analyzing grades 1 and 2 together. They did not, however, remove either grade 1 or 2 from their classification. When they intend to change their classification (have both grades classified under one histology number), they omit one code from their book (make it obsolete) and change the definition for the other code. The 2008 WHO book did not make either ICD-O-3 code obsolete, so we continue to collect the cases as designated by the pathologist. If the controversy is settled before the next WHO classification, you may see changes in the codes.

Additionally, since the 2008 WHO book was written, there have been some clinical papers challenging the designation of grade 3. They contend that grade 3 can be mistaken for low-grade.

The grades in follicular lymphoma are based on the number of centroblasts per high powered field (HPF). The number of centroblasts for grade 1 is 0-5; for grade 2 is 6-15, for grade 3a and 3b is >15 centroblasts. 3a has centrocytes and 3b is without centrocytes.


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